Injection syringe and an injection needle for use therewith



March 11, 1958 5. J. PIEKEZ' 2,826,196

INJECTION SYRINGE AND AN INJECTION NEEDLE FOR USE THEREWITH Filed Feb.15, 1954 f IN V EN TOR. .Su'ntm 'j'ukcmnes Vek f M United States PatentINJECTION SYRINGE AND AN INJECTION NEEDLE FOR USE THEREWITH SimonJohannes Piek, s-Hertogenhosch, Netherlands, assignor to JohanVoorhorst, The Hague, Netherlands Application February 15, 1954, SerialNo. 410,409 1 Claim. (Cl. 128-221) The present invention relates to aninjection syringe and an injection needle for use therewith.

In the past there has been a serious problem in the use of injectionsyringes having a removable injection needle attached thereto, resultingfrom the flow of contaminated fluid back into the injection syringebecause of the negative pressure created in the injection syringe uponthe removal of the needle.

It is an object of the present invention to provide an injection syringehaving a detachable needle whereby the positive pressure is maintainedin the injection syringe which prevents the backflow of contaminatedfluid into the injection syringe from the injection needle.

The type of syringe and injection needle contemplated by the presentinvention is of the type as described in U. S. Patent application SerialNo. 285,620, now Patent Number 2,699,777 issued January 18, 1955.

In accordance with the present invention the above and other objects areaccomplished by a construction whereby an externally threaded syringenipple has its end provided with a fitting strip which is adapted to bebrought into sealing engagement with another fitting strip on acounter-nipple having internal threads, said counter nipple having afitting strip which surrounds the entrance to the hollow needle, and atleast the syringe nipple or the counter-nipple being provided with anair passage communicating with the atmosphere, one end of said airpassage ending between the screw and the fitting strip of thecounternipple.

In illustration of the invention an embodiment of the injection syringewill be described with reference to the accompanying drawing, in which:

Fig. 1 is a perspective showing of the injection syringe and Fig. 2 is alongitudinal section on the line 11-11 in Fig. 1 on a larger scale.

According to the drawing the nipple 1 of the injection syringe 2 whichmay be of a conventional construction, is provided with an axial fluidpassage 3 and with an externally threaded portion 8. The injectionneedle 5 is provided with a counter nipple 6 which is internally "iceprovided with a threaded portion 9 which fits on the screw-threadedportion 8 of the syringe nipple 1.

The needle counter-nipple 6 which comprises a transverse bore 7functioning as an air passage is-just as the syringe nipple 1sodimensioned that upon screwing the needle nipple 6 on the syringe nipple1 the end of the latter, which end is constructed as a fitting strip,will come into sealing engagement with the internal fitting strip 10 ofthe needle nipple 6, which fitting strip 10 surrounds the entrance tothe hollow needle 5.

If after the administration of an injection the needle nipple 6 isunscrewed from the syringe nipple 1 for the purpose of replacing theinjection needle by a fresh needle the needle nipple and the syringenipple will be axially and relatively displaced, so that at the sametime the sealing engagement between the end of the syringe nipple 1 andthe internal fitting strip 10 of the needle nipple 6 will be interruptedand via the air passage 7 in the needle nipple 6 air will be admitted tothe axial fluid passage 3 in the syringe nipple 1. Thus injection fluidwhich has remained behind in the injection needle 5 and which may becontaminated will be prevented from being sucked back and fromcontacting the syringe nipple 1 or the interior of the injection syringewhen the needle nipple 6 is taken off the syringe nipple 1.

Though a preferred embodiment of my invention has been illustrated anddescribed herein, it is to be understood that certain changes may bemade as improvement to the features herein disclosed, which do not inany way depart from the true spirit and scope of the appended claim.These may include alteration of the disposition of the air passage inthe needle nipple and the like to form a slot, not shown.

I claim:

An injection syringe in which the injection needle is detachablyconnected to the syringe reservoir by means of an externally threadedsyringe nipple and a threaded portion of the injection needlecounter-nipple, said externally threaded syringe nipple having its endprovided with a fitting strip coming into sealing engagement with afitting strip on said counter-nipple, said syringe nipple beingthreadably engaged with said counter-nipple, said fitting strip on saidcounter-nipple surrounding the entrance to the said injection needle, atleast one of said nipples being provided with an air passagecommunicating with the atmosphere and ending in a hollow portion in saidcounter-nipple between a screw thread and a fitting strip.

References Cited in the file of this patent UNITED STATES PATENTS1,547,557 Brody July 28, 1925 1,596,004 De Bengoa Aug. 17, 1926 FOREIGNPATENTS 902,925 France Ian. 3, 1945

